Letter Re: Earthquake Hazard, Risk, and Mitigation

Tuesday, Feb 8, 2011

James:
Thank you for your interesting and informative web site and mission.  Just a few short thoughts on earthquake hazard, risk, and mitigation, since it's a pet interest of mine for some time and I come at it from a slightly different background than some.  I'm a southeastern US resident in an area about 300 miles give or take from the New Madrid fault zone.  My community is actually located in the second most seismically active area east of the Rockies, so I do have some personal investment in the topic.  Additionally, I have more than 20 years' experience in disaster services, so i've got both some practical experience and I've had some time to study and think about stuff.

Hazard is the potential for physical activity that can cause damage to structures and inhabitants.  Risk is the human behavior(s) that leads to greater or lesser damages given the particular hazard(s) discussed.  Mitigation is the action(s) taken to reduce risk and damage. 

The greatest danger for many families living in earthquake country is right in their own homes.  Gas-fueled water heaters are fairly unstable when lifted and pushed sideways, and since you already have a natural gas line, usually copper in the Central US, and a flame (pilot light), an unsecured gas water heater is like having your own family catastrophe waiting with your bath water.  Copper line breaks, uncontrolled gas bleeds out of the lines, and it ignites.  This was a problem in California and other western states in the past -- in areas that mostly require seismic shutoff valves today on natural gas lines entering occupied properties.  During, IIRC, the Loma Prieta earthquake, they discovered a few useful facts like this, including the follow-on treat that events that break gas lines also often break water lines, so you get a fire that you have little to no means to extinguish.  Turned out it was hard to open rolling sheet metal fire station doors too. 

Fortunately for those who don't live in places where building codes have caught up to physical realities as much as to political ones, it is simple and cheap to fix this potential catastrophe. Hardware stores sell, very inexpensively, "plumbing tape" or "hardware tape" that is basically thin, 1 inch or so wide strips of rolled sheet metal with holes every inch or so.  One simply takes this material, wraps it around their water heater at about 2/3 height of the heater, then nail it off securely to wall studs.   Shazam.  It won't fix all your problems, and there are lots of other topics we could discuss, but this is the first one I mention when I meet folks who live in or very near earthquake hazard zones.

This happens to be the bicentennial of the famous New Madrid series of quakes that caused 2 waterfalls on the Mississippi, church bells to ring in Boston, windows to rattle in D.C., and formed the largest land area lake in Tennessee by the Mississippi River basically flowing backwards for a while.  The eyewitness accounts are quite riveting.  The fact is that Eastern/Central US quakes cause shaking in a roughly 10 times larger area than in California simply due to the stiffer, older underlying rock.  Damages will likely be even greater geographically distributed because we have practically nothing in the built environment to protect people, and our people have no clue what to do to prepare or respond. 

With Best Regards, In Christ, - River S.


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